| changeset 70744 | b605c9cf82a2 |
| parent 70742 | e21c6b677c79 |
| child 70745 | be8e617b6eb3 |
--- a/src/HOL/Data_Structures/Tree2.thy Sun Sep 22 19:04:11 2019 +0200 +++ b/src/HOL/Data_Structures/Tree2.thy Mon Sep 23 07:57:58 2019 +0200 @@ -39,4 +39,7 @@ lemma finite_set_tree[simp]: "finite(set_tree t)" by(induction t) auto +lemma set_tree_empty: "set_tree t = {} \<longleftrightarrow> t = Leaf" +by (cases t) auto + end